Molly's Cafe 🍵

This repo contains the source code for Molly's Cafe, a work in progress neocity / portfolio !

Here's a list of all the features that are currently implemented :

• Real-time monitoring of the server
  • Docker containers
  • Systemd services
  • CPU temperature
  • TCP / UDP connections
  • Dirty memory
  • Opened file descriptors
  • Running processes
  • Idle Uptime
  • RAM usage
  • Free disk space
• List of my school projects (with live updates)
• Pistache (my blogging engine) posts (with live updates)
• Real-time Paris weather with dynamic background (clouds, rain, ...) and the following informations :
  • Sunrise
  • Sunset
  • Local time
  • Cloudiness
  • Felt temperature
  • Humidity
  • Wind speed
• Cursor of other users (opt-out through a small checkbox)
• Currently listening on Strawberry Player
• Number of users currently connected
• Live progress of a Leitner System
• Sleep tracking (through Apple's Shortcuts app)
• Template rendering for the front-end

Note

Platform support

The Go code can only be compiled on Linux (maybe MacOS ?) due to :

1. The usage of Go's syscall package
2. The usage of a lot of /proc / /sys file parsing
3. Relying on systemd for service management

Looking for bugs ?

Go ahead, break everything you can (well not too much), I'll be happy to fix it and learn more!

Exploring the code

If you're interested in some specific part of the code, here's a simple table of content :

• Netcode
• Monitoring
• 2D Rendering

Netcode

The netcode is the part of the code that handles (for the moment) the websocket connections.

• clients.go : Handles connections and handles broadcasting / mutexes
• proto.go : Creation, modification of custom packets
• packets.go : Hashmap of packets, used by watchdogs to quickly edit packets and reflect the changes to the clients
• main.go : Handling of HTTP -> Websocket upgrade, along with other private APIs and static file serving

Monitoring

The monitoring part of the code is where the program is gathering data from other programs / from the kernel.

Services

The services part of the code, is where we gather the state of specific services running through systemd, and where we gather the state of docker containers.

This part of the code is completely done using polling, so I made the choice of also making it real-time, meaning that any change to a docker container or a systemd service will be broadcasted instantly.

Watchdogs

Currently each watchdog is a goroutine, and each watchdog is started in the init function.

A watchdog is a goroutine that will poll a specific value, and if the value is different from the previous one, it will update the corresponding packet, and broadcast it to the clients, and then sleep for a specific amount of time.

File	Description	Remarks
Containers.go	Watches every docker containers	-
CPUTemp.go	Watches the CPU temperature (compatible with k10temp / coretemp)	-
DirtyMem.go	Watches the amount of dirty memory	-
DiskSpace.go	Watches the amount of free disk space	-
IdleUptime.go	Watches the amount of time the system has been idle	-
InternetSpeed.go	Downloads a file every hour and measure download speed	Probably cycle through multiple servers to be a good netizen
LoggedUsers.go	Watches the amount of logged users	Disabled for now, because I don't want to fork who, and must parse /var/run/wtmp instead
ManualService.go	Watches the state of a systemd service	-
MemUsage.go	Watches the amount of memory used	-
MonitorSchoolProjects.go	Polls a directory containing school projects to dynamically update a table in the front-end	-
OpenFiles.go	Watches the amount of opened fds	-
PistachePosts.go	Polls a directory containing posts to dynamically update a list of blog-post in the front-end	-
RunningProcesses.go	Watches the amount of running processes	-
TcpUdp.go	Watches the amount of opened TCP / UDP sockets	-
Weather.go	Checks the weather of any configured city every 5 minutes	-

Implementation notes

They're designed to be as simple, efficient and modular as possible (for my use case).

Docker containers states are watched through docker events.

systemd services states are watched through a probably overthought method using inotify on the /run/systemd/units directory.

2D Rendering

The 2D rendering part of the code is done using just a HTML5 canvas, and a handmade 2D rendering engine called Sirius.

You can display its debugging side-card on the front-end by changing the sirius_debug local storage value to true through the browser's devtools, and then reloading the page.

Or you can run this JavaScript code in the console :

localStorage.setItem("sirius_debug", "true");
window.location.reload();

NOTE: to disable it, just set the sirius_debug local storage value to false and reload the page.

Sirius

Sirius is a very basic object-oriented 2D rendering engine. It contains only the bare minimum to be able to render a 2D scene, with very basic physics, as always, I have a lot of ideas to improve it for future ideas.

You can see the entire source code of the engine here

Features

• Static 2D rendering
• Moving 2D rendering (basic physics)
• Click events
• Particles
• Animations
• Advanced physics

ADrawable

You can create a drawable object by creating extending the ADrawable class, and implementing the tick method.

The tick method is called every frame whether the object is enabled or not.

AMovable

An AMovable is an ADrawable that can move, it has a velocity, every frame, the velocity is added to the position of the object.

Credits

Thanks to Miko for most of the graphics !

Assets

File	Usage	Author
cloud_0.png	Cloud variant 0	Miko
cloud_1.png	Cloud variant 1	Miko
cloud_2.png	Cloud variant 2	Miko
cloud_3.png	Cloud variant 3	Miko
cloud_4.png	Cloud variant 4	Miko
cloud_icon.png	Cloudiness icon	Miko
cursor.png	Other user's cursors	?
moon.png	Moon icon for sunset time	Miko
placeholder.png	Placeholder	Molly
raindrop_0.png	Raindrop	Molly
sun.png	Sun icon for sunrise time	Miko
clock.png	Clock icon to display current time	Miko
thermometer.png	Thermometer icon to display felt temperature	Miko
humidity.png	Humidity icon to display humidity	Miko
wind.png	Wind icon to display wind speed	Miko